DESCRIPTION (Applicant's Abstract): Human gene therapy is an exciting area in modern medicine. However, at the present time the methods used to efficiently transduce human hematopoietic stem cells need to be improved. In addition, while it has been possible to target gene expression to the erythroid lineages, very little work has addressed the question of how to target genes to macrophages. The long-term objectives of this application are to develop new vectors for the delivery of heterologous genes into hematopoietic cells, and specifically into macrophages in order to develop realistic approaches to gene therapy of metabolic diseases. Using adeno-associated virus (AAV) vectors, which are capable of introducing foreign DNA into the chromosome of non-dividing cells and hematopoietic progenitors, and the macrophage specific CD11b promoter, the applicant aims to perform studies demonstrating that this vector/promoter combination can result in high level expression of heterologous genes in macrophages. Therefore, the specific aims are to produce and study these new vectors in the following steps: (1) To develop efficient inducible packaging cell line systems to generate high titer AAV virus stocks; (2) To transduce murine and human bone marrow cells with AAV vectors with macrophage specific promoters in order to determine whether he can drive expression of a reporter gene in macrophages; and (3) To transplant bone marrow cells into recipient mice, and to investigate expression of the reporter genes in macrophages. It is anticipated that the results of these studies will lead to new information regarding methods for production of high titers of recombinant AAV virus, new information regarding the use of macrophage specific promoters for gene therapy applications, which are especially relevant to metabolic diseases.